The present invention relates generally to gas turbine power generation, and, more specifically, to heat exchangers therein.
In a gas turbine engine, ambient air is pressurized in a compressor and mixed with fuel in a combustor for generating hot combustion gases. Energy is extracted from the combustion gases in a turbine which powers the compressor through a shaft joined thereto. Output power may be extracted from the same turbine powering the compressor, or from a low pressure turbine disposed downstream therefrom. The output shaft power may be used for driving an electrical generator in a typical application.
The efficiency of the turbine system is based in large part on efficient compression of the air, coupled with efficient combustion of the air mixed with fuel for producing the combustion gases from which energy is extracted by the turbine. The air discharged from the compressor is relatively hot due to the compression heating thereof and has a corresponding temperature, pressure, and density upon entering the combustor.
Various forms of heat exchangers are known in the turbine field. In one example, a heat exchanger known as a recuperator uses the hot combustion gases for further heating the compressed air prior to use in the combustor. In this way, otherwise waste heat from the turbine is reintroduced into the turbine cycle.
Furthermore, it is also known to inject steam into the combustion gases for increasing the mass flow thereof for also increasing overall efficiency of the turbine cycle. However, recuperators and steam injection require corresponding apparatus therefor and increase the complexity and cost of the turbine system.
In a separate development of heat exchangers, evaporative cooling may be used for cooling air below its wet bulb temperature and up to its dew point temperature in an improved cooling cycle. This Maisotsenko Cycle is disclosed in various configurations in various patents, including U.S. Pat. Nos. 5,453,223; 6,497,107; and 6,581,402. Additional information for this cycle is available on the worldwide web at idalextechnologies.com.
Accordingly, it is desired to improve heat exchanger performance in turbine cycles, for example, employing yet another advancement in the Maisotsenko Cycle.